Conventional railroad vehicles, particularly high-speed railroad vehicles include ones equipped with a plug door. The plug door has a door form such that the outer surface thereof is flush with the outer surface of a vehicle body when the doorway is closed. This plug door allows reductions in air resistance and noise such as wind noise.
Furthermore, as for an airtight maintaining device included in the plug door, Patent Literature 1 listed below discloses a configuration in which a piston rod of a cylinder device 4 is extended, thereby causing a link member 5 to turn and press a door 1 in a closed position toward airtight packing 3 so as to maintain the air tightness of the door 1.